Optical force sensor for robotic surgical system

ABSTRACT

According to an aspect of the present disclosure, a surgical instrument is provided and includes a housing; an elongate shaft extending from the housing; and a tool assembly supported by a distal portion of the elongate shaft, the tool assembly including first and second jaw member. The at least one of the first and second jaw members is moveable relative to the other jaw member between a neutral configuration in which the first and second jaw members are spaced apart relative to one another; and a clamping configuration in which the first and second jaw members are approximated relative to one another with tissue grasped therebetween, the first jaw member defining a cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application filed under 35U.S.C. § 371(a) of International Patent Application Serial No.PCT/US2016/062138, filed Nov. 16, 2016, which claims the benefit of andpriority to U.S. Provisional Patent Application Ser. No. 62/257,564,filed Nov. 19, 2015, the entire disclosure of which is incorporated byreference herein.

BACKGROUND

Robotic surgical systems have been used in minimally invasive medicalprocedures. During a medical procedure, the robotic surgical system iscontrolled by a surgeon interfacing with a user interface. The userinterface allows the surgeon to manipulate an end effector that acts ona patient. The user interface includes an input controller that ismoveable by the surgeon to control the robotic surgical system.

The robotic surgical system includes a surgical robot that is associatedwith the user interface. The surgical robot includes linkages thatsupport a surgical instrument. The surgical instrument can include oneor more jaw members that act on tissue of the patient during a surgicalprocedure. As the clinician manipulating the end effector is remote tothe patient, it is important to accurately determine the forces exertedon the tissue by the jaw members.

Accordingly, there is a need for accurately determining forces exertedon or by the jaw members of the surgical instrument during a surgicalprocedure.

SUMMARY

This disclosure relates generally to optical force sensors that aredisposed in one or more jaw members of a surgical instrument of arobotic surgical system. The optical force sensors directly measure thedeflection of the respective jaw member in one or more directions todetermine force exerted on or by the respective jaw member. The directmeasurement of the deflection of the respective jaw member has beenshown to provide an accurate measure of the force exerted on or by therespective jaw member.

The measured force can be used to provide feedback to a clinicianengaged with the user interface of the robotic surgical system. Inaddition, the measured force can be used to enhance the function of avariety of instruments including, but not limited to, a grasper, astapler (monolithic or two-part fasteners), electrosurgical forceps, andan endoscopic suturing device. For example, when the surgical instrumentis a grasper, the measured force can be used to determine a forceexerted on tissue by the grasper or to determine if an item (e.g., asuture) is slipping between two graspers. Additionally, when theinstrument is a stapler, the measured force can be used to determine aforce exerted to clamp tissue between the jaw members to prevent underor over clamping of the tissue before application of a one or two-partstaple. Further, when the instrument is an electrosurgical forceps, themeasured force can be used to optimize sealing, cutting, and/orcoagulating of tissue between the jaw members. In addition, when theinstrument is an endoscopic suturing device the measured force can beused to optimize the force exerted on a suture.

According to an aspect of the present disclosure, a surgical instrumentis provided and includes a housing; an elongate shaft extending from thehousing; and a tool assembly supported by a distal portion of theelongate shaft, the tool assembly including first and second jaw member.The at least one of the first and second jaw members is moveablerelative to the other jaw member between a neutral configuration inwhich the first and second jaw members are spaced apart relative to oneanother; and a clamping configuration in which the first and second jawmembers are approximated relative to one another with tissue graspedtherebetween, the first jaw member defining a cavity.

The surgical instrument further includes an optical force sensorconfigured to determine a force exerted to tissue. The optical forcesensor includes a light source; a reflector disposed within the cavityof the first jaw member and configured to reflect light emitted from thelight source; a light receiver configured to sense an amount of lightreflected from the light source; and a processor in communication withthe light receiver and configured to determine deflection of the firstjaw member from the amount of sensed light, the deflection of the firstjaw member correlated to a force exerted by the first jaw member totissue.

The light source may be disposed within the housing.

The optical force sensor may include a light guide extending between thelight source and the cavity.

The light receiver may be disposed within the housing and incommunication with the light guide such that light reflected from thereflector passes through the light guide.

In use, light reflected from the reflector may have at least oneproperty different than light emitted towards the reflector, the atleast one property is at least one of a phase or a wavelength.

The light receiver may be disposed within the cavity.

The first jaw member may have a tissue contacting surface opposing thesecond jaw member and an outer surface opposite the tissue contactingsurface. The first and second jaw members may have a distractingconfiguration in which the outer surface of the first jaw member isengaged with tissue.

In the clamping configuration, the first jaw member may be deflected ina first direction, and in the distracting configuration, the first jawmember may be deflected in a second direction opposite the firstdirection. The processor may be configured to determine a direction ofdeflection of the first jaw member from the amount of light received bythe light receiver.

The reflector may be disposed orthogonal to an axis of transmittance oflight emitted from the light emitter.

The reflector may be disposed at an angle relative to an axis oftransmittance of the light emitted from the light emitter in a range ofabout 5° to about 85°.

The reflector may be concave. The concavity of the reflector may beconfigured to direct the entire amount of light emitted from the lightsource towards the light detector when the first jaw member is in theneutral configuration.

The light source may be at least one of a microLED or a laser diode.

According to a further aspect of the present disclosure, a tool assemblyis provided and includes a jaw member defining a cavity; and an opticalforce sensor configured to determine a force exerted to tissue by a jawtool assembly, the tool assembly defining a cavity. The optical forcesensor includes a first light source; a reflector disposed within acavity of the tool assembly and configured to reflect light emitted fromthe first light source; a light receiver configured to sense an amountof emitted by the first light source and reflected by the reflector; anda processor in communication with the light receiver and configured todetermine deflection of the first jaw member from the amount of sensedlight, the deflection of the first jaw member correlated to a forceexerted by the first jaw member to tissue.

The optical force sensor may include a second light source. Thereflector may be configured to reflect light emitted from the secondlight source. The light receiver may be configured to sense an amount oflight emitted by the second light source and reflected by the reflector.

The cavity may be defined by a first sidewall and a second sidewallperpendicular to the first sidewall. The first light source may beconfigured to emit light through an opening in the first sidewall andthe second light source may be configured to emit light through anopening in the second sidewall.

The first light source may be configured to emit light having a firstproperty and the second light source is configured to emit light havinga second property different from the first property, the light detectordifferentiating between sensed light from the first light source andsensed light from the second light source.

According to still another aspect of the present disclosure, a method isprovided for determining a force applied to tissue by a jaw member of atool assembly. The method includes engaging tissue with a jaw member ofa tool assembly such that the jaw member is deflected; emitting lightfrom a light source towards a reflector disposed within a cavity definedin within the jaw member; sensing an amount of light from the firstlight source reflected by the reflector with a light detector; anddetermining the force applied to the tissue by the jaw member from theamount of sensed light.

The engaging tissue with the jaw member may include at least one ofengaging tissue with a tissue contacting surface of the jaw member in aclamping configuration or engaging tissue with an outside surface of thejaw member opposite the tissue contacting surface in a distractingconfiguration.

The determining of the force applied to tissue by the jaw member mayinclude a configuration of the jaw member based on the amount of sensedlight.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure are described hereinbelow withreference to the drawings, which are incorporated in and constitute apart of this specification, wherein:

FIG. 1 is a schematic illustration of a user interface and a roboticsystem in accordance with the present disclosure;

FIG. 2 is a schematic illustration of a surgical instrument of therobotic system inserted into a body cavity of a patient;

FIG. 3 is a schematic illustration of an optical force sensor of thesurgical instrument of FIG. 2 provided in accordance with the presentdisclosure;

FIG. 4 is a schematic illustration of the first jaw member of thesurgical instrument of FIG. 2 including the optical force sensor of FIG.3 in a neutral configuration;

FIG. 5 is a schematic illustration of the optical force sensor of FIG. 4in a closing configuration;

FIG. 6 is a schematic illustration of the optical force sensor of FIG. 4in an opening configuration;

FIG. 7A is a schematic illustration of the first jaw member of thesurgical instrument of FIG. 2 including another optical force sensorprovided in accordance with the present disclosure in a neutralconfiguration;

FIG. 7B is a schematic illustration of the optical force sensor of FIG.7A in a closing configuration;

FIG. 7C is a schematic illustration of the optical force sensor of FIG.7A in an opening configuration;

FIG. 8A is a schematic illustration of the first jaw member of thesurgical instrument of FIG. 2 including another optical force sensorprovided in accordance with the present disclosure in a neutralconfiguration;

FIG. 8B is a top view of a cavity of the first jaw member of FIG. 8A;

FIG. 9A is a schematic illustration of the first jaw member of thesurgical instrument of FIG. 2 including another optical force sensorprovided in accordance with the present disclosure in a neutralconfiguration;

FIG. 9B is a top view of a cavity of the first jaw member of FIG. 9A;

FIG. 10A is a schematic illustration of the first jaw member of thesurgical instrument of FIG. 2 including another optical force sensorprovided in accordance with the present disclosure in a neutralconfiguration;

FIG. 10B is a schematic illustration of the optical force sensor of FIG.7A in a closing configuration;

FIG. 10C is a schematic illustration of the optical force sensor of FIG.7A in an opening configuration;

FIG. 11 is a side view of two end effectors of two surgical instrumentseach including an optical force sensor provided in accordance with thepresent disclosure; and

FIG. 12 is a flowchart illustrating a method of generating forcefeedback for a robotic surgical system in accordance with the presentdisclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. Asused herein, the term “clinician” refers to a doctor, a nurse, or anyother care provider and may include support personnel. Throughout thisdescription, the term “proximal” refers to the portion of the device orcomponent thereof that is closest to the clinician and the term “distal”refers to the portion of the device or component thereof that isfarthest from the clinician.

This disclosure relates generally to optical force sensors that aredisposed in one or more jaw members of a surgical instrument of arobotic surgical system. The optical force sensors directly measure thedeflection of the respective jaw member in one or more directions todetermine force exerted on or by the respective jaw member. The opticalforce sensor includes a light source, a light guide, a reflector, and alight receiver. The light guide is in communication with the lightsource to transmit light produced by the light source into a cavitydefined within a jaw member of the surgical instrument. An amount of thetransmitted light is reflected off of the reflector and returned intothe light guide. The light receiver measures an amount of light returnedinto the light guide to determine the deflection of the jaw member. Thereflector is supported within the cavity such that as the jaw member isdeflected, the amount of light returned into the light guide varies.

Referring to FIG. 1, a robotic surgical system 1 is shown generally as arobotic system 10, a processing unit 30, and a user interface 40. Therobotic system 10 generally includes linkages 12 and a robot base 18.The linkages 12 moveably support an instrument 20 which is configured toact on tissue. The linkages 12 may be in the form of arms or links eachhaving an end 14 that supports an instrument 20 which is configured toact on tissue. In addition, the ends 14 of the linkages 12 may includean imaging device 16 for imaging a surgical site “S”. The user interface40 is in communication with robot base 18 through the processing unit30.

The user interface 40 includes a display device 44 which is configuredto display three-dimensional images. The display device 44 displaysthree-dimensional images of the surgical site “S” which may include datacaptured by imaging devices 16 positioned on the ends 14 of the linkages12 and/or include data captured by imaging devices that are positionedabout the surgical theater (e.g., an imaging device positioned withinthe surgical site “S”, an imaging device positioned adjacent the patient“P”, imaging device 56 positioned at a distal end of an imaging linkage52). The imaging devices (e.g., imaging devices 16, 56) may capturevisual images, infra-red images, ultrasound images, X-ray images,thermal images, and/or any other known real-time images of the surgicalsite “S”. The imaging devices transmit captured imaging data to theprocessing unit 30 which creates three-dimensional images of thesurgical site “S” in real-time from the imaging data and transmits thethree-dimensional images to the display device 44 for display.

The user interface 40 also includes input devices or handles attached togimbals 70 which allow a clinician to manipulate the robotic system 10(e.g., move the linkages 12, the ends 14 of the linkages 12, and/or theinstruments 20). Each of the gimbals 70 is in communication with theprocessing unit 30 to transmit control signals thereto and to receivefeedback signals therefrom. Additionally or alternatively, each of thegimbals 70 may include control interfaces or input devices (not shown)which allow the surgeon to manipulate (e.g., clamp, grasp, fire, open,close, rotate, thrust, slice, etc.) the instruments 20 supported at theends 14 of the linkages 12.

Each of the gimbals 70 is moveable to move the ends 14 of the linkages12 within a surgical site “5”. The three-dimensional images on thedisplay device 44 are orientated such that movement of the gimbals 70moves the ends 14 of the linkages 12 as viewed on the display device 44.It will be appreciated that the orientation of the three-dimensionalimages on the display device may be mirrored or rotated relative to viewfrom above the patient “P”. In addition, it will be appreciated that thesize of the three-dimensional images on the display device 44 may bescaled to be larger or smaller than the actual structures of thesurgical site “S” permitting the surgeon to have a better view ofstructures within the surgical site “S”. As the gimbal 70 is moved, theinstruments 20 are moved within the surgical site “S”. Movement of theinstruments 20 may also include movement of the ends 14 of the linkages12 which support the instruments 20.

For a detailed discussion of the construction and operation of a roboticsurgical system 1, reference may be made to U.S. Pat. No. 8,828,023, theentire contents of which are incorporated herein by reference.

With reference to FIG. 2, an instrument 20 is inserted into a bodycavity “C” of a patient “P” through a port or trocar 80 to access thesurgical site “S”. The instrument 20 includes a housing or body 110, anelongate shaft 120, and an end effector 130. The body 110 includes aninterface 112 that couples to an instrument drive unit (IDU) 90 whichprovides mechanical energy or input for manipulating the instrument 20.The IDU 90 may also provide electrical and/or optical energy to theinstrument 20 through the interface 112. In addition, the instrument 20may provide feedback signals, electrical, mechanical, and/or optical, toIDU 90. The IDU 90 is in communication with the processing unit 30(FIG. 1) to receive signals for manipulating the instrument 20 and toprovide feedback signals from the instrument 20 and the IDU 90 to theprocessing unit 30 as described in detail below.

The elongate shaft 120 extends from the body 110 and is articulable inthree degrees of freedom (DOF) relative to the body 110. It will beappreciated that the body 110 is moveable into and out of the trocar 80to provide a fourth DOF. The body 110 includes an articulation mechanism(not explicitly shown) to articulate the elongate shaft 120 in responseto mechanical input from the IDU 90.

The end effector 130 is supported at a distal end 128 of the elongateshaft 120 and includes a first jaw member 140 and a second jaw member150 that are moveable relative to one another between an open positionand a closed position. As shown, each of the first and second jawmembers 140, 150 pivot relative to one another about a pin 134 (FIG. 3)of the end effector 130; however, one of the first or second jaw members140, 150 may be fixed relative to the elongate shaft 120 with the otherone of the first or second jaw members 140, 150 moveable relative to thefixed jaw member. The IDU 90 includes a motor 94 that is associated withthe end effector 130 to transition the first and second jaw members 140,150 between the open and closed positions. Some IDUs 90 may include twoor more motors 94 that may actuate one or more features of instrument20. One or more of the motors 94 may be associated with respectivecables to actuate one or more features of the instrument 20. Thesefeatures may include, for example, articulation of the jaws 140, 150 orend effector 130 in one or more degrees of freedom. As detailed below,the IDU 90 includes a torque or force sensor 96 that generates adirection signal indicative of whether the motor 94 is transitioning thefirst and second jaw members 140, 150 towards the closed position ortowards the open position.

Referring to FIGS. 3 and 4, the first jaw member 140 defines a cavity142 that includes an optical force sensor 200 in accordance with thepresent disclosure. The optical force sensor 200 includes a light source210, a light guide 220, a reflector 230, and a light receiver 240. Asshown, the light source 210 is disposed in the body 110 (FIG. 2);however, it is contemplated that the light source 210 (e.g., a microLEDor laser diode) may be disposed in the elongate shaft 120 or the endeffector 130 (e.g., a yoke 132 of the end effector 130 or the first orsecond jaw member 140, 150). The light guide 220 may be in the form ofan optical fiber (e.g., fiber optic cable) that extends from the body110, through the elongate shaft 120, and into the end effector 130. Thelight guide 220 includes a proximal end 222 that is in opticalcommunication with the light source 210 to receive light provided by thelight source 210 and a distal end 228 disposed in the cavity 142 definedwithin the first jaw member 140.

The reflector 230 is supported by the first jaw member 140 within thecavity 142. The walls defining the cavity 142 may be treated with lightabsorbing material, a non-reflective material, or a diffusing materialto increase the sensitivity of the optical force sensor 200. Thereflector 230 is aligned with the distal end 228 of the light guide 220such that light transmitted through the distal end 228 of the lightguide 220 is in a light cone “LC” having a transmittance axis “T” thatis directed towards the reflector 230. It will be appreciated that theamount of light at the transmittance axis “T” is greater than an amountof light at a point within the light cone “LC” a distance away (e.g., aradial distance) from the transmittance axis “T”. The reflector 230 is aflat mirror that is disposed substantially orthogonal to thetransmittance axis “T” such that light transmitted through the distalend 228 of the light guide 220 is reflected off of the reflector 230back towards the distal end 228 of the light guide 220 in a reflectedlight cone “RLC” having a reflectance axis “R”. It will be appreciatedthat an amount of light at the reflectance axis “R” is greater than anamount of light at a point within the reflected light cone “RLC” spacedapart (e.g., a radial distance) from the reflectance axis “R”.

The light receiver 240 is disposed within the body 110 of the surgicalinstrument 100 in optical communication with the proximal end 222 of thelight guide 220. The light receiver 240, which may in some instances bea photocell, may be configured to sense an amount of light reflectedthrough the light guide 220 from the reflector 230.

It is contemplated that the reflector 230 may include a fluorescingmaterial such that light emitted from the reflector 230 has a differentwavelength than light striking the reflector 230. For example, thereflector 230 may be a scintillator mirror.

It is envisioned that the second jaw member 150 may also include anoptical force sensor 200 disposed within a cavity 152 defined within thesecond jaw member 150. The optical force sensor 200 disposed within thesecond jaw member 150 may share the first light source 210 with theoptical force sensor 200 disposed within the first jaw member 140. Theoptical force sensor 200 disposed within the second jaw member 150functions in a similar manner to the optical force sensor 200 disposedwithin the first jaw member 140 as described below and will not bedescribed in further detail herein.

With reference to FIGS. 4-6, the first jaw member 140 has a rest orneutral configuration (FIG. 4), a clamping configuration (FIG. 5), and adistracting configuration (FIG. 6). In the neutral configuration, thefirst jaw member 140 is subject to little or no force (e.g., transverseforce) such that the reflectance axis “R” is substantially aligned withthe transmittance axis “T”. The most amount of light may be reflectedback to the light receiver 240 when the reflectance axis “R” is alignedwith the transmittance axis “I”.

In the clamping configuration, the first and second jaw members 140, 150are moving towards the closed configuration. As shown in FIG. 5, thefirst jaw member 140 is in the clamping configuration moving in a firstor closing direction as represented by arrow “CD” in FIG. 5. In theclamping configuration, the first and second jaw members 140, 150 mayengage an obstruction “0” (e.g., tissue, bone, vessel, another surgicalinstrument, etc.) such that the first jaw member 140 is deformed ordeflected by a deflection force. The deflection of the first jaw member140 moves the reflector 230 within the cavity 142 of the first jawmember 140 which misaligns the reflectance axis “R” from thetransmittance axis “T”. When the reflectance axis “R” is misaligned withthe transmittance axis “T”, the amount of light returned through thelight guide 220, and thus sensed by the light receiver 240, is less thanwhen the first jaw member 140 is in the neutral configuration (i.e.,when the reflectance axis “R” is aligned with the transmittance axis“T”). The difference (e.g., reduction) in the amount of light receivedby the light receiver 240 from the neutral configuration is indicativeof the deflection of the first jaw member 140. With the deflection ofthe first jaw member 140 from the neutral configuration known, thedeflection force exerted by the first jaw member 140 on the obstruction“O” can be determined.

In the distracting configuration, the first and second jaw members 140,150 are moving towards the open configuration. As shown in FIG. 6, withthe first jaw member 140 in the distracting configuration, the first jawmember 140 moves in a second or opening direction as represented byarrow “OD” in FIG. 6. In the distracting configuration, the first jawmember 140 is engaged with an obstruction “O” (e.g., tissue, bone,vessel, another surgical instrument, etc.) on an outer surface of thefirst jaw member 140 such that the first jaw member 140 is deflected bya deflection force. The deflection of the first jaw member 140 moves thereflector 230 within the cavity 142 of the first jaw member 140 whichmisaligns the reflectance axis “R” from the transmittance axis “T” asthe first jaw member 140. When the reflectance axis “R” is misalignedwith the transmittance axis “T”, the amount of light returned throughthe light guide 220, and thus sensed by the light receiver 240, is lessthan when the first jaw member 140 is in the neutral configuration(i.e., when the reflectance axis “R” is aligned with the transmittanceaxis “T”). The difference (e.g., reduction) in the amount of lightreceived by the light receiver 240 from the neutral configuration isindicative of the deflection of the first jaw member 140. With thedeflection of the first jaw member 140 from the neutral configurationknown, the deflection force exerted by the first jaw member 140 on theobstruction “O” can be determined. It is contemplated that the first jawmember 140 may include cuts or reliefs (not explicitly shown) in thewalls to promote deflection of the first jaw member 140 and/or toincrease sensitivity of the optical force sensor 200.

The optical force sensor 200 may include a processor 202 (FIG. 3) thatreceives a signal from the light receiver 240 indicative of the amountof light received and correlates or calculates the amount of lightreceived into a deflection force exerted by or on the first jaw member140. The processor 202 may be calibrated at the time of manufacture toassociate a change in an amount of light received by the light receiver240 with a deflection force of the first jaw member 140. Additionally oralternatively, the processor 202 may be calibrated before or during asurgical procedure to compensate for changes in the jaw member 140(e.g., a permanent deformation, obstructions in the cavity “C”, orconditions at the light source 210 or the light receiver 240).

As detailed above, the difference between the amount of light receivedby the light receiver 240 in the neutral configuration and the amount oflight received by the light receiver 240 when the first jaw member 140is deflected, in either the clamping or distracting configuration, isreduced. To differentiate between the clamping configuration and thedistracting configuration, the processor 202 or the processing unit 30receives a direction signal from the torque sensor 96 of the motor 94indicative of a direction of movement of the first jaw member 140 (i.e.,towards the open position or towards the closed position) to determinethe configuration of the first jaw member 140, and thus, the directionof the deflection of the first jaw member 140. The processor 202 or theprocessing unit 30 may utilize the direction signal to calculate thedeflection force as the first jaw member 140 may deflect asymmetricallyin response to a given deflection force.

In aspects, the optical force sensor 200 may include a light receiver240′ disposed within the cavity 142 of the first jaw member 140 thatsends a signal to the processor 202 indicative of an amount of lightreceived by the light receiver 240′. The light receiver 240′ is offsetfrom the reflectance axis “R” and is disposed within a reflected lightcone “RLC” of light transmitted through the distal end 228 of the lightguide 220 and reflected off of the reflector 230. As shown in FIG. 5,when the first jaw member 140 is in the clamping configuration, thelight receiver 240′ receives an amount of light less than an amount oflight received in the neutral configuration. When the first jaw member140 is in the distracting configuration, the light receiver 240′receives an amount of light greater than an amount of light received inthe neutral configuration as shown in FIG. 6. By offsetting the lightreceiver 240′ from the reflectance axis “R” in the neutralconfiguration, the direction of the deflection of the first jaw member140 and, thus, the direction of the force exerted by or on the first jawmember 140 can be determined from the increase or decrease in the amountof light received by the light receiver 240. Thus, the extent and thedirection of the deflection force can be determined without the need fora direction signal from the torque sensor 96. It will be appreciatedthat by placing the light receiver 240′ within the cavity 142, light maybe continually transmitted through the distal end 228 of the light guide220 without interfering with light reflected off of the reflector 230 tothe light receiver 240 through the light guide 220.

In some aspects, the light receiver 240′ may be used in conjunction withthe light receiver 240 to provide a direction signal to the processor202 and/or provide a verification of the extent of the deflection force.

Referring now to FIGS. 7A-C, another optical force sensor 1200 isprovided in accordance with the present disclosure. The optical forcesensor 1200 is similar to the optical force sensor 200, as such, onlythe differences will be detailed below with like structures representedwith a similar label including a “1” preceding the previous label.

The optical force sensor 1200 includes a light source 1210, a lightguide 1220, a reflector 1230, and a light receiver 1240. The reflector1230 is supported within the cavity 142 of the first jaw member 140 atan angle offset from a plane “P” orthogonal to the distal end 1228 ofthe light guide 1220 in the neutral configuration of the first jawmember 140. The angle may be in a range of about 5° to about 85° (e.g.,about 15°). In the neutral configuration of the first jaw member 140,the reflectance axis “R” is offset from the transmittance axis “T” withthe distal end 1228 of the light guide 1220 within the reflected lightcone “RLC” of light transmitted through the distal end 1228 of the lightguide 1220.

In use, when the first jaw member 140 is in the neutral configuration,an amount of light is reflected into the distal end 1228 of the lightguide 1220 which is transmitted through the light guide 1220 and ontothe light receiver 1240. The amount of light transmitted onto the lightreceiver 1240 is measured by the light receiver 1240. When the first jawmember 140 is in the clamping configuration, as shown in FIG. 7B, anamount of light is reflected off of the reflector 1230 into the distalend 1228 of the light guide 1220, and thus onto the light receiver 1240,is less than the amount of light reflected into the distal end 1228 whenthe first jaw member 140 is in the neutral configuration. When the firstjaw member 140 is in the dissecting configuration as shown in FIG. 7C,an amount of light reflected into the distal end 1228 of the light guide1220, and thus onto the light receiver 1240, is greater than the amountof light reflected into the distal end 1228 when the first jaw member140 is in the neutral configuration.

As detailed above, by disposing the reflector 1230 within the cavity 142of the first jaw member 140, at an angle relative to the distal end 1228of the light guide 1220, such that the reflectance axis “R” is offsetfrom the transmittance axis “T”, when the first jaw member 140 is in theneutral configuration, the optical force sensor 1200 senses the extentand direction of the deflection of the first jaw member 140.

In aspects, the optical force sensor 1200 includes a light receiver1240′ disposed within the cavity 142 of the first jaw member 140 thatsends a signal to a processor 1202 of the optical force sensor 1200indicative of an amount of light received by the light receiver 1240′.The light receiver 1240′ is offset from the reflectance axis “R” and isdisposed within a reflected light cone “RLC”. As shown in FIG. 7B, whenthe first jaw member 140 is in the clamping configuration, the lightreceiver 1240′ receives an amount of light less than an amount of lightreceived in the neutral configuration. When the first jaw member 140 isin the distracting configuration, the light receiver 1240′ receives anamount of light greater than an amount of light received in the neutralconfiguration as shown in FIG. 7C. By offsetting the light receiver1240′ from the reflectance axis “R”, the extent and the direction of thedeflection of the first jaw member 140 is determined by the amount oflight measured by the light receiver 1240′.

In some aspects, the light receiver 1240′ is disposed within the cavity142 and is aligned with the reflectance axis “R” when the first jawmember 140 is in the neutral configuration. Similar to the optical forcesensor 200 detailed above, when the light receiver 1240′ is aligned withthe reflectance axis “R”, when the first jaw member 140 is in either theclamping or distracting configurations, the amount of light received bythe light receiver 1240′ is less than when the first jaw member 140 isin the neutral configuration. In such aspects, the optical force sensor1200 includes a processor 1202 that receives a direction signal from atorque sensor 96 (FIG. 2) associated with the motor 92 to determine thedirection of the deflection of the first jaw member 140.

It is contemplated that the optical force sensor 1200 may utilize thelight receiver 1240 to determine the direction of the deflection of thefirst jaw member 140 and the light receiver 1240′ to determine theextent of the deflection of the first jaw member 140. Alternatively, theoptical force sensor 1200 may utilize the light receiver 1240 todetermine the direction and the extent of the deflection of the firstjaw member 140 and utilize the light receiver 1240′ to verify the extentof the deflection of the first jaw member 140.

Referring to FIGS. 8A-B, another optical force sensor 2200 is providedin accordance with the present disclosure. The optical force sensor 2200is similar to the optical force sensor 200, as such, only thedifferences will be detailed below with like structures represented witha similar label including a “2” preceding the previous label.

The optical force sensor 2200 includes a light source 2210, a lightguide 2220, a reflector 2230, and a light receiver 2240. The reflector2230 is supported within the cavity 142 of the first jaw member alignedwith the plane “P” orthogonal to a distal end 2228 of the light guide2220. The reflector 2230 is concave in a first direction and flat in asecond direction aligned with the opening and closing directions “OD”,“CD” which is orthogonal to the first direction. The concavity of thereflector 2230 focuses light transmitted through the distal end 2228 ofthe light guide 2220 on the distal end 2228 of the light guide 2220 in adirection substantially parallel to the opening and closing directions“OD”, “CD”. As such, the reflected light cone “RLC” is substantiallylinear at the distal end 2228 of the light guide 2220 in a directionsubstantially parallel to the opening and closing directions “OD”, “CD”.

In use, the optical force sensor 2220 functions in a manner similar tothe optical force sensor 200 for detecting deflection of the first jawmember 140 towards and away from the second jaw member 150 (i.e., in theopening direction “OD” or in closing direction “CD”). By reflectinglight transmitted through the distal end 2228 of the light guide 2220 ina substantially linear reflected light cone “RLC”, the concavity of thereflector 2230 isolates deflection of the first jaw member 140 in theopening and closing directions “OD”, “CD” from deflection of the firstjaw member 140 in a first transverse direction “TD1” or a secondtransverse direction “TD2”. Thus, the concavity of the reflector 2230may increase the accuracy of the optical force sensor 2220 for detectingan extent of the deflection of the first jaw member 140 in the openingand closing directions “OD”, “CD”. It is contemplated that the reflector2230 concave in both the first and second directions such the reflector2230 focuses light transmitted through the distal end 2228 of the lightguide 2220 to a point or a focused spot.

In aspects, the optical force sensor 2200 includes a light receiver2240′ disposed within the cavity 142 of the first jaw member 140. Thelight receiver 2240′ is positioned offset from a transmittance axis “T”of the light cone “LC” of light transmitted through the distal end 2228of the light guide 2220 and aligned with the distal end 2228 of thelight guide 2220 such that the light receiver 2240′ receives asubstantially linear reflected light cone “RLC”. In use, the lightreceiver 2240′ functions substantially similar to the light receiver240′ and may have increased accuracy for detecting an extent of thedeflection of the first jaw member 140.

Referring to FIGS. 9A and 9B, another optical force sensor 3200 isprovided in accordance with the present disclosure. The optical forcesensor 3200 is similar to the optical force sensor 1200, as such, onlythe differences will be detailed below with like structures representedwith a similar label replacing the first numeral “1” with a numeral “3”.

The optical force sensor 3200 includes a light source 3210, a lightguide 3220, a reflector 3230, and a light receiver 3240. The reflector3230 is supported within the cavity 142 of the first jaw member 140 atan angle offset from a plane “P” orthogonal to a distal end 3228 of thelight guide 3220. The reflector 3230 is concave in a first direction andflat in a second direction aligned with the opening and closingdirections “OD”, “CD” which is orthogonal to the first direction. Theconcavity of the reflector 3230 focuses light transmitted through thedistal end 3228 of the light guide 3220 on the distal end 3228 of thelight guide 3220 in a direction substantially parallel to the openingand closing directions “OD”, “CD”. As such, the reflected light cone“RLC” is substantially linear at the distal end 3228 of the light guide3220 in a direction substantially parallel to the opening and closingdirections “OD”, “CD”.

In use, the optical force sensor 3220 functions in a manner similar tothe optical force sensor 1200 for detecting deflection of the first jawmember 140 towards and away from the second jaw member 150 (i.e., in theopening direction “OD” or in closing direction “CD”). By reflectinglight transmitted through the distal end 3228 of the light guide 3220 ina substantially linear reflected light cone “RLC”, the concavity of thereflector 3230 isolates deflection of the first jaw member 140 in theopening and closing directions “OD”, “CD” from deflection of the firstjaw member 140 in a first transverse direction “TD1” or a secondtransverse direction “TD2”. Thus, the concavity of the reflector 3230may increase the accuracy of the optical force sensor 3220 for detectingan extent of the deflection of the first jaw member 140 in the openingand closing directions “OD”, “CD”.

In aspects, the optical force sensor 3200 includes a light receiver3240′ disposed within the cavity 142 of the first jaw member 140 thatsends a signal to a processor 3202 of the optical force sensor 3200indicative of an amount of light received by the light receiver 3240′.The light receiver 3240′ is offset from the reflectance axis “R” and isdisposed within a reflected light cone “RLC” of light transmittedthrough the distal end 3228 of the light guide 3220. When the first jawmember 140 is in the clamping configuration, the light receiver 3240′receives an amount of light less than an amount of light received in theneutral configuration. When the first jaw member 140 is in thedistracting configuration, the light receiver 3240′ receives an amountof light greater than an amount of light received in the neutralconfiguration. By offsetting the light receiver 3240′ from thereflectance axis “R”, the extent and the direction of the deflection ofthe first jaw member 140 is determined by the amount of light measuredby the light receiver 3240′.

In some aspects, the light receiver 3240′ is disposed within the cavity142 and is aligned with the reflectance axis “R” when the first jawmember 140 is in the neutral configuration. Similar to the optical forcesensor 200 detailed above when the light receiver 3240′ is aligned withthe reflectance axis “R”, when the first jaw member 140 is in either theclamping or distracting configurations, the amount of light received bythe light receiver 3240′ is less than when the first jaw member 140 isin the neutral configuration. In such aspects, the optical force sensor3200 includes a processor 3202 that receives a direction signal from atorque sensor 96 (FIG. 2) associated with the motor 92 to determine thedirection of the deflection of the first jaw member 140.

Referring now to FIGS. 10A-C, another optical force sensor 4200 isprovided in accordance with the present disclosure. The optical forcesensor 4200 is similar to the optical force sensor 200, as such, onlythe differences will be detailed below with like structures representedwith a similar label including a “4” preceding the previous label.

The optical force sensor 4200 includes a first light source, a secondlight source, a first light guide 4220, a second light guide 4224, areflector 4230, and a light receiver 4246. The reflector 4230 issupported within the cavity 142 of the first jaw member 140 at an angleoffset from the plane “P” that is orthogonal to the distal end 4228 ofthe first light guide 4230.

In use, the first light source, the first light guide 4220, and thelight receiver 4246 function in a similar manner to the similarcomponents of the optical force sensor 1200 detailed above. As such,only the differences will be described below for reasons of brevity.

The second light source may be positioned within the body 110 (FIG. 2);however, it is contemplated that the second light source may be disposedin the elongate shaft 120 or the end effector 130 (e.g., the first orsecond jaw member 140, 150). The second light guide 4224 may be in theform of an optical fiber (e.g., fiber optic cable) that extends from thebody 110, through the elongate shaft 120, and into the end effector 130.The second light guide 4224 includes a proximal end 4225 that is inoptical communication with the second light source to receive lightprovided by the second light source and a distal end 4226 disposed inthe cavity 142 defined within the first jaw member 140. The distal end4226 of the second light guide 4224 is shaped such that lighttransmitted through the distal end 4226 defines a second transmittanceaxis “2T” orthogonal to the transmittance axis “T” of light transmittedthrough a distal end 4228 of a first light guide 4220. As shown, thedistal end 4226 of the second light guide 4224 is disposed at about a45° angle to transmit a light cone “LC” towards the reflector 4230;however, the second light guide 4224 may curve adjacent the distal end4226 such that the distal end 4226 is flat, similar to the distal end4228 of the first light guide 4220. The distal end 4226 of the secondlight guide 4224 is positioned offset from the reflectance axis “2R” oflight transmitted through the distal end 4226. Light received at thedistal end 4226 of the second light guide 4224 is transmitted throughthe second light guide 4224 to the light receiver 4246. The lightreceiver 4246 may be disposed within the body 110 of the surgicalinstrument 100 and is configured to sense an amount of light reflectedfrom the reflector 4230 and returned through the second light guide4224.

The first and second light sources may produce light having propertiesdifferent from one another such that the light transmitted from one ofthe first and second light sources and ultimately reflected from thelight reflector 4230 may be differentiated from light produced by theother one of the first and second light sources. For example, the lightsources may be time or frequency modulated to differentiate the lightfrom each source. Other differentiation techniques may also be used. Insome instances the light sources may be selected to emit a specificwavelength of light in a range of about 10¹⁶ m to about 1 m in length.The light receiver 4246 may be configured detect the differentiatedlight emitted from each of the light sources so that the amount of lightreflected to the receiver 4246 from each of the sources may be measured.

In aspects, the distal end 4228 of the first light guide 4220 is offsetfrom the reflectance axis “R” and within the reflected light cone “RLC”of light transmitted through the distal end 4226 of the second lightguide 4224. Similarly, the distal end 4226 of the second light guide4224 is offset from the reflectance axis “R”, and is within thereflected light cone “RLC” of light transmitted through the distal end4228 of the first light guide 4220. The light receiver 4246 may bepositioned in optical communication with a proximal end 4215 of thesecond light guide 4224 to measure an amount of light transmittedthrough the distal end 4228 of the first light guide 4220, reflected offof the reflector 4230, and into the distal end 4226 of the second lightguide 4224. The amount of light measured by the light receiver 4246 isindicative of the deflection of the first jaw member 140 in the openingor closing direction “OD”, “CD”. The light receiver 4246 may also bepositioned in optical communication with a proximal end 4222 of thefirst light guide 4220 to measure an amount of light transmitted throughthe distal end 4226 of the second light guide 4224, reflected off of thereflector 4230, and into the distal end 4228 of the first light guide4220. By each of the first and second light sources producing lighthaving different properties, the light sources can continuously producelight and the light receiver 4246 can continuously measure an amount oflight from each of the light sources.

The first and second light signals are transmitted to a processor 4202or the processing unit 30 (FIG. 1) which calculates the direction andextent of deflection of the first jaw 140. The processor 4202 or theprocessing unit 30 calculates deflection of the first jaw 140 in theopening or closing direction “OD”, “CD” from the first light signal andcalculates deflection of the first jaw 140 in the first or secondtransverse direction “1TD”, “2TD” from the second light signal.

In some aspects, the optical force sensor 4200 includes third lightreceiver 4246 disposed within the cavity 142 of the first jaw member140. The third light receiver 4246 is positioned between the distal end4228 of the first light guide 4220 and the distal end 4226 of the secondlight guide 4224 offset from the reflectance axes “R”, “2R” and withinthe reflected light cone “RLC” of light transmitted through the distalend 4228 of the first light guide 4220 and the distal end 4226 of thesecond light guide 4224, respectively. The light receiver 4246 may beconfigured to differentiate light produced by the first light sourcefrom light produced by the second light source such that the lightreceiver 4246 can measure an amount of light received that is producedby the first light source and an amount of light received that isproduced by the second light source. The light receiver 4246 generates afirst light signal indicative of the amount of light received that isproduced by the first light source and a second light signal indicativeof the amount of light received that is produced by the second lightsource.

In particular aspects, the distal end 4228 of the first light guide 4220may be shaped such that the reflected light cone “RLC” of lighttransmitted through the distal end 4228 of the first light guide 4220 inthe clamping, distracting, and neutral configurations does not contactthe distal end 4226 of the second light guide 4224. Similarly, thedistal end 4226 of the second light guide 4224 may be shaped such thatthe reflected light cone “RLC” of light transmitted through the distalend 4226 of the second light guide 4224 does not contact the distal end4228 of the first light guide 4220 in response to deflection of thefirst jaw 140.

As detailed and shown above, the optical force sensors (i.e., opticalforce sensors 200, 1200, 2200, 3200, 4200) are associated with the firstjaw member 140 of the end effector 130; however, it is contemplated, asmentioned above, that second jaw member 150 may also include an opticalforce sensor to determine a force exerted on or by the second jaw member150 as represented by optical force sensor 200′ as shown in FIG. 3.Additionally or alternatively, the instrument 20 may include an opticalforce sensor 200″ in the yoke 132 of the end effector 130 to measureforces exerted on or by the yoke 132.

Briefly referring back to FIG. 2, a pair of optical force sensors 1200′,1200″ may be disposed within the elongate shaft 120 of the instrument 20to determine the force exerted between the elongate shaft 120 and thetrocar 80. Specifically, an optical force sensor 1200′ is disposed in aportion of the elongate shaft 120 disposed within the trocar 80 andoptical force sensor 1200″ is disposed in a portion of the elongateshaft 120 of the instrument 20 outside of the trocar 80. The differencebetween a force measured by the optical force sensor 1200′ and a forcemeasured by the optical force sensor 1200″ is indicative of the forceexerted between the elongate shaft 120 and the trocar 80.

Referring now to FIG. 11, a method of detecting suture slippage isdescribed in accordance with the present disclosure. The method includesgrasping a suture 300 with a first end effector 130 and a second endeffector 130′. Each of the first and second end effectors 130, 130′ hasa first jaw member 140 and a second jaw member 150. Each first jawmember 140 includes an optical force sensor (e.g., optical force sensor200, 1200, 2200, 3200, or 4200), as detailed above.

The suture 300 is grasped between the first jaw members 140 of the firstand second end effectors 130, 130′. The first and second end effectors130, 130′ are in a closed position such that the second jaw member 150of each of the first and second end effectors 130, 130′ also engages thesuture 300. Additionally or alternatively, the first jaw members 140and/or the second jaw members may include grasping structures 148, 158(e.g., teeth) that cooperate to engage the suture 300.

With the suture 300 grasped between the first jaw members 140 of thefirst and second end effectors 130, 130′, the end effectors 130, 130′are drawn apart to apply a tension force “TF” to the suture 300.

To determine if the suture 300 is slipping with respect to one or bothof the end effectors 130, 130′, the force applied by each of the firstjaw members 140 to the suture 300 is determined by the optical forcesensor disposed in the first jaw members 140. The forces applied by eachof the first jaw members 140 are summed together and compared to thetension force “TF” applied to the end effectors 130, 130′. If the sum ofthe forces applied by the first jaw members 140 is substantially equalto the tension force “TF” applied to the end effectors 130, 130′, thesuture 300 is not slipping relative to the end effectors 130, 130′.Alternatively, if the sum of the forces applied by the first jaw members140 is less than the tension force “TF” applied to the end effectors130, 130′, the suture 300 is slipping relative to at least one of theend effectors 130, 130′. It will be appreciated, that the force appliedto the suture by the first jaw members 140 may be the sum of forcesapplied in more than one axes (e.g., in the opening or closing directionand in the first or section transverse directions as detailed above) ofthe respective first jaw member 140.

By comparing the forces applied by each of the first jaw members 140, itmay be determined which of the end effectors 130, 130′ the suture 300 isslipping relative to. If the force applied by one of the first jawmembers 140 is significantly less than the force applied by the otherone of the first jaw members 140, the suture 300 is slipping relative toat least the first jaw member 140 applying the lower force to the suture300. In response to the slippage of the suture 300, a closure force ofthe respective end effector 130, 130′ may be increased to engage thesuture 300 between the first and second jaw members 140, 150 of therespective end effector 130, 130′ to prevent the slippage. The slippageof the suture 300 can then be redetermined as detailed above. The endeffectors 130, 130′ may be repositioned on the suture 300 beforeredetermining the slippage of the suture 300.

Referring to FIGS. 1 and 12, a method 500 for generating force feedbackfor a robotic surgical system is described in accordance with thepresent disclosure. Initially, a clinician engages an input deviceattached to a gimbal 70 of the user interface 40 to actuate aninstrument 20 associated with the input device and the gimbal 70. Toengage the input device, the clinician may move the input device, andthus the gimbal 70, or move a control (e.g., a button, a lever, an arm)of the input device. The input device and/or gimbal 70 generates andsends an actuation signal indicative of the actuation of the inputdevice and/or gimbal 70 to the processing unit 30 (Step 510). Theprocessing unit 30 analyzes the actuation signal and generates anactuation control signal which is transmitted to the IDU 90 associatedwith the instrument 20 (Step 520).

In response to the actuation control signal, the IDU 90 activates themotor 92 to actuate the instrument 20 (e.g., to actuate the end effector130 to move the first and second jaw members 140, 150 towards the closedposition) (Step 530). During actuation of the instrument 20, an opticalforce sensor disposed in one of the first or second jaw members 140, 150(e.g., optical force sensor 200, 1200, 2200, 3200, 4200) is periodicallyor continuously measuring the deflection of one of the first or secondjaw members 140, 150 to determine the force exerted by one of the firstor second jaw members 140, 150. The optical force sensor generates andtransmits a force signal to the processing unit 30 in response to themeasured deflection of one of the first or second jaw members 140, 150(Step 540). In response to the force signal, the processing unit 30generates and transmits a feedback signal to a feedback controller 41 ofthe user interface 40 (Step 550). In response to the feedback signal,the feedback controller 41 activates a feedback motor 49 to providefeedback to the clinician engaged with the input device (Step 560).

As detailed above, the optical force sensor generates a force signalincluding an extent and a direction of the force exerted by one of thefirst or second jaw members 140, 150. When the optical force sensorgenerates a force signal that is only indicative of the extent of theforce exerted by one of the first or second jaw members 140, 150 (e.g.,when the optical force sensor is optical force sensor 200), theprocessing unit 30 receives a direction signal from the torque sensor 96associated with the motor 92 (Step 534). The processing unit 30 receivesand analyzes both the force signal and the direction signal to generatethe feedback signal. Alternatively, the direction signal may betransmitted to a processor 202 of the optical force sensor (Step 536)which combines the direction signal with the extent of the deflection ofone of the first or second jaw members 140, 150 to generate the forcesignal (Step 540).

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Any combination ofthe above embodiments is also envisioned and is within the scope of theappended claims. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of particularembodiments. Those skilled in the art will envision other modificationswithin the scope of the claims appended hereto.

What is claimed:
 1. A surgical instrument comprising: a housing; anelongate shaft extending from the housing; a tool assembly supported bya distal portion of the elongate shaft, the tool assembly includingfirst and second jaw member, at least one of the first and second jawmembers moveable relative to the other jaw member between: a neutralconfiguration in which the first and second jaw members are spaced apartrelative to one another; and a clamping configuration in which the firstand second jaw members are approximated relative to one another withtissue grasped therebetween, the first jaw member defining a cavity; andan optical force sensor configured to determine a force exerted totissue, the optical force sensor including: a light source; a reflectordisposed within the cavity of the first jaw member and configured toreflect light emitted from the light source; a light receiver configuredto sense an amount of light reflected from the light source; and aprocessor in communication with the light receiver and configured todetermine deflection of the first jaw member from the amount of sensedlight, the deflection of the first jaw member correlated to a forceexerted by the first jaw member to tissue.
 2. The surgical instrumentaccording to claim 1, wherein the light source is disposed within thehousing.
 3. The surgical instrument according to claim 2, wherein theoptical force sensor includes a light guide extending between the lightsource and the cavity.
 4. The surgical instrument according to claim 3,wherein the light receiver is disposed within the housing and incommunication with the light guide such that light reflected from thereflector passes through the light guide.
 5. The surgical instrumentaccording to claim 4, wherein light reflected from the reflector has atleast one property different than light emitted towards the reflector,the at least one property is at least one of a phase or a wavelength. 6.The surgical instrument according to claim 1, wherein the light receiveris disposed within the cavity.
 7. The surgical instrument according toclaim 6, wherein the first jaw member has a tissue contacting surfaceopposing the second jaw member and an outer surface opposite the tissuecontacting surface, the first and second jaw members have a distractingconfiguration in which the outer surface of the first jaw member isengaged with tissue.
 8. The surgical instrument according to claim 7,wherein in the clamping configuration the first jaw member is deflectedin a first direction and in the distracting configuration the first jawmember is deflected in a second direction opposite the first direction,the processor being configured to determine a direction of deflection ofthe first jaw member from the amount of light received by the lightreceiver.
 9. The surgical instrument according to claim 1, wherein thereflector is disposed orthogonal to an axis of transmittance of lightemitted from the light emitter.
 10. The surgical instrument according toclaim 1, wherein the reflector is disposed at an angle relative to anaxis of transmittance of the light emitted from the light emitter in arange of about 5° to about 85°.
 11. The surgical instrument according toclaim 1, wherein the reflector is concave.
 12. The surgical instrumentaccording to claim 11, wherein the concavity of the reflector isconfigured to direct the entire amount of light emitted from the lightsource towards the light detector when the first jaw member is in theneutral configuration.
 13. The surgical instrument according to claim 1,wherein the light source is at least one of a microLED or a laser diode.14. A tool assembly comprising: a jaw member defining a cavity; anoptical force sensor configured to determine a force exerted to tissueby a jaw tool assembly, the tool assembly defining a cavity, the opticalforce sensor including: a first light source; a reflector disposedwithin a cavity of the tool assembly and configured to reflect lightemitted from the first light source; a light receiver configured tosense an amount of emitted by the first light source and reflected bythe reflector; and a processor in communication with the light receiverand configured to determine deflection of the first jaw member from theamount of sensed light, the deflection of the first jaw membercorrelated to a force exerted by the first jaw member to tissue.
 15. Thetool assembly according to claim 14, wherein the optical force sensorincludes a second light source, the reflector configured to reflectlight emitted from the second light source, the light receiverconfigured to sense an amount of light emitted by the second lightsource and reflected by the reflector.
 16. The tool assembly accordingto claim 15, wherein the cavity is defined by a first sidewall and asecond sidewall perpendicular to the first sidewall, the first lightsource configured to emit light through an opening in the first sidewalland the second light source configured to emit light through an openingin the second sidewall.
 17. The tool assembly according to claim 15,wherein the first light source is configured to emit light having afirst property and the second light source is configured to emit lighthaving a second property different from the first property, the lightdetector differentiating between sensed light from the first lightsource and sensed light from the second light source.
 18. A method ofdetermining a force applied to tissue by a jaw member of a toolassembly, the method comprising: engaging tissue with a jaw member of atool assembly such that the jaw member is deflected; emitting light froma light source towards a reflector disposed within a cavity defined inwithin the jaw member; sensing an amount of light from the first lightsource reflected by the reflector with a light detector; and determiningthe force applied to the tissue by the jaw member from the amount ofsensed light.
 19. The method according to claim 18, wherein engagingtissue with the jaw member includes at least one of engaging tissue witha tissue contacting surface of the jaw member in a clampingconfiguration or engaging tissue with an outside surface of the jawmember opposite the tissue contacting surface in a distractingconfiguration.
 20. The method according to claim 18, wherein determiningthe force applied to tissue by the jaw member includes a configurationof the jaw member based on the amount of sensed light.